The invention resides in a method of producing a self-focusing reflection grating for a microspectrometer comprising flexible foil strips, which carry the grating structure and which are joined by support structures of a microspectrometer housing.
In SPIE, Vol. 503, Application, Theory and Fabrication of Periodic structures (1984), pages 23 and 24, a configuration including a concave grating is described and shown wherein a silicon wafer having a reflection grating is clamped, cylindrically bent, onto the front side of a flat multimode wave guide (see FIG. 3, page 24). A similar arrangement is known from FIG. 1b of JP-OS-90311 of May 21, 1985. OPTICS LETTERS, Vol. 6, No. 12, December 1981, pages 639-641 discloses a planar Rowland spectrometer with a flexible reflection grating which was produced on a thin glass substrate by way of holography and ion etching. This flexible grating is mounted in a tentering frame and pressed against the curved front side of the wave guide of the spectrometer (see FIG. 3 on page 640). Whereas in the manufacture of the wave guide, the curved front faces of thirty structures are concurrently polished (see page 639, left columns, bottom), the flexible reflection gratings must be individually produced.
Based on this state-of-the-art, it is the object of the present invention to provide also for the manufacture of the reflection gratings a method which is suitable for a mass production of the reflection gratings wherein their radius of curvature, their width and their height is selectable within wide limits.